The Siemens 3RH2911-1FB11-ZX95 is a SIRIUS auxiliary switch block that snaps onto the front of 3RT2 contactors and 3RH2 contactor relays, adding one normally-open and one normally-closed auxiliary contact. It uses screw-type terminals and is rated for a maximum of 10 A, with specific current ratings defined per voltage level — 6 A at 24 V, 6 A at 125 V, 6 A at 230 V, 6 A at 250 V, and 3 A at 400 V, among others. For AC-15 duty, it carries 10 A at 24 V, 4.7 A at 60 V, 3 A at 110 V, 1.2 A at 220 V, 0.5 A at 440 V, and 0.26 A at 600 V.
Mounting and fit
Snap-on mounting means this block clips directly onto the front of the contactor or contactor relay without tools — no additional DIN-rail space consumed. Dimensions are 36 mm wide, 37.5 mm high, and 43.7 mm deep, so it adds minimal depth to the assembly. The IP20 protection on the front is standard for enclosed panels; keep it behind a cabinet door or cover.
Contact configuration and ratings
The switch provides one leading NO contact and one lagging NC contact, meaning the NO closes before the NC opens during actuation — important for sequencing in safety or interlock circuits. The insulation voltage is rated at 690 V AC with pollution degree 3, and surge voltage resistance is 6 kV. Mechanical life is 10 million switching cycles typical, with a contact reliability of one faulty switching per 100 million operations at 17 V, 1 mA — solid for PLC-level signal switching.